1. Field of the Invention
Systems and methods consistent with the present invention generally relate to a radio frequency (RF) communication system having a chaotic signal generator and a method of generating a chaotic signal, and more particularly, to an RF communication system having a chaotic signal generator which is less power-consuming, small in size and easy to construct and a method of generating a chaotic signal.
2. Description of the Related Art
A spread-spectrum communications technique transmits signal using a much wider band than the bandwidth of the signal. A representative example of using this technique is a code division multiple access (CDMA) which uses narrowband carriers. Additionally, there also is a way of using wideband carriers.
In order to use narrowband carriers, frequency of the data for transmission is modulated to be narrower than the frequency band of the carrier signal, while the frequency band of the data for transmission is modulated to be wider than the frequency band of the carrier signal in order to use wideband carriers.
Carriers in the spread-spectrum communications usually use sinuous waves and pulses. The sinuous waves or pulses are up-converted to a certain frequency to transmit data. To this end, a transmitter of a communication system needs components for up-converting the carriers from a baseband to a certain frequency band, while a receiver needs components to down-convert the received carriers back to the baseband.
More specifically, the transmitter includes a voltage controller oscillator (VCO) to generate a frequency to transmit data, and a phase locked loop (PLL) to lock the generated frequency from external influence. The transmitter also requires an up-mixer to up-convert the baseband carriers at the frequency generated by the VCO.
Accordingly, the receiver requires a down-mixer to down-convert the received carriers back to baseband.
Because the transmitter has components such as VCO, PLL, and up-mixer, power consumption increases. Additionally, components such an up-mixer is quite large and therefore, the size of the transmitter also increases. Likewise, there usually is a big and power-consuming receiver as the receiver uses components such as a down-mixer.
IEEE 802.15.4a standard has proposed the use of chaotic signals to transmit data.
IEEE 802.15.4a is the Task Group for the standardization of low-rate navigation sensor network, which proposed a next-generation communication incorporating a hybrid of IEEE 802.15.4 ZigBee and IEEE 802.15.3 Ultra Wide Band (UWB) communications with the functions of navigation and low-rate power consumption.
The chaotic signal modulation has been proposed in an attempt to achieve low-rate power consumption. The chaotic signal modulation can be designed in a simple RF structure at the hardware level, and circuits, which are generally required for an RF communication system such as VCO, PLL and mixer, are not necessary. Accordingly, power consumption can be reduced to 5 mW one-third of general power consumption, by using the chaotic signal modulation.
Therefore, a low-rate RF communication system will be achieved, if a chaotic signal modulation is appropriately applied.